this is test #1:

5
5
8
13
27
14
answer 3

It's seems to me that if we rearrange these 6 stones in such two piles:
1. 27 + 5 + 5 = 37
2. 13 + 14 + 8 = 35
we'll get diffrence 2!

Where is the dirty trick?

never mind... already get it!
the first number in the sequence is the number of stones!